“When you get over the top of the hill and you’re already accelerating down toward the ground and you start feeling that G-force as that car reaches the bottom of that hill, the body senses a change in motion,” says Longley, an emergency room physician.

“Because it’s an unfamiliar force and an unfamiliar direction, it automatically sends signals and again you’re going to be releasing adrenalin from your adrenal glands and that will trigger your heart rate.”

While the motion gets the heart racing, it’s what the eyes see and the brain receives that causes the not-so-great uneasiness and the real possibility of vertigo, Longley said. The good news is it’s only temporary.

“When you’re on a roller coaster, some of the motion of the train on the tracks is so fast that the brain is actually getting mixed signals,” he said.

Jeff Hornick is Director of Design and Engineering at Busch Gardens Tampa, home to seven thrill coasters, including SheiKra, a floorless, diving coaster that reaches 60 miles per hour.

He says computer simulation models help find the balance between a ride that thrills, but doesn’t kill.

“We design around what is called the heart line. So whatever design it is, we’re making sure that we are designing right around where your heart is in your chest,” he said. “And the reason we do that is that we don’t want the blood to rush to your head or to your toes for an extended period of time.”

G-forces – that fantastic speed coasters are known for – is only one aspect engineers worry about, Hornick said. The thrills they want to provide can’t come at too dangerous a pace.

“Most of the times you want to have your highs and lows. So you want to have points where you have lots of high Gs, and maybe negative Gs,” said Hornick, who has been involved on designs of many coasters at Busch Gardens, including the soon-to-openFalcon’s Fury. “But you also want points where you can reset yourself and prepare for the next element.”

Those reset ‘breaks’ come and go too fast for most riders to notice. But Longley says every inch of the body reacts.

“Those forces are experienced by all of your organs: your brain, your heart, your eyes, your blood vessels, etc,” he said. “You really don’t get into a lot of trouble until about nine Gs.”

None of the seven thrill coasters at Busch Gardens reach that extreme level of force – most are closer to 4 Gs, according to roller coaster fan websites.

But the rides do have strict height requirements and stern warnings to riders who might be pregnant, or have weakened hearts or back or neck problems – that litany of warnings you hear as you wait in line. Longley says those who are healthy – and love the thrill of a coaster – are good to go.

“The statistics show that you have a higher chance of a serious injury driving to the amusement park or home from the amusement park than you actually do riding a roller coaster,” he said.

Still, for some people, the adrenalin of just standing in line is too much to take. Longley says the heart rate is usually highest before you get on a ride, or during that initial climb. It’s only human, he said.

“There’s really not a whole lot you can do. You can learn to deal with that feeling of the adrenalin. But there’s really not anything you can do about preventing the adrenalin from actually being there,” he said.

That fear some people feel near coasters can be very real. Hornick said that’s why Busch Gardens designs rides to go near guests who want to keep their feet planted firmly on the ground. That way the less adventurous – or those too young or short to ride - can enjoy the rush, he said.

People who want to overcome that anxiety do have options, Longley said.

“Sure, you can overcome that with say, behavioral therapy - just like any other phobia. It’s kind of funny to think of it in terms like that, but it is actually a sort of phobia. And it would require behavioral therapy to kind of get over that fear of not even wanting to get on the ride.”

When you start riding, you think, Oh Man, this looks great. And then you start realizing how high you are getting. And you start getting really nervous, like, how high will we go?

Hornick says he knows that not all riders are smiling when the ride hits the brakes. When what he calls “adverse reactions” do happen, certain rides can often be blamed.

“A lot of people get sick on the continuous forces, like a spinning type of ride, like if you have a fast carousel or something where like that where you are just spinning, or the swinging ships as well,” said Hornick, an avid coaster rider. “That continuous cycle over and over again is where a lot of the uneasiness and queasy feels.”

Dr. Longley said it’s best to not have a completely empty stomach when getting on a coaster. But also avoid eating an enormous meal before getting in line. And hold back on the liquid intake.

“When your body is moving, accelerating, decelerating up and down, umm, your stomach is doing the same thing, your intestines are doing the same thing, and the increase in motion and the fluid wave that may be inside your belly from a 22-ounce beer, or even a soda, or whatever liquid you so choose to drink, will really enhance those sensations,” he said.

Or you can take a tip from those who feel queasy on a cruise ship or drive along mountain roads. Take a few Dramamine.

“There definitely are medications you can take to blunt that effect of, of the nausea and vomiting and motion sickness associated with those rides,” he said. “So that’s a great option.”

And then there's always a safer option: sitting on the sidelines and smiling as screaming riders fly by.

Related Content

The days may be numbered for the giant wooden roller coaster off I-95. The iconic Dania Beach Hurricane, which closed down in 2011, may soon have a new owner who has no intention of keeping it around.

Aventura-based Master Development has a contract on the land underneath the millions of feet of wood and concrete to build what it calls DaniaLive. The development will include shops, a hotel, restaurants and apartments.

The Dania Beach Hurricane was the largest wooden roller coaster in Florida. Depending on your definition of "is" and "roller coaster," it might still hold that title. The ride shut down in April 2011, but the monstrous jungle of lumber still looms over I-95. The track is still there. The trains are still there. The Hurricane just doesn't run anymore.

And now the coaster's owners are trying to give the entire thing away to charity. But, no surprise, that's proving difficult. (You can listen to that story above.)